Santa – who lives at the Norf Powl, according to the address our six-year-old wrote on the envelope in his charmingly bonkers handwriting – has an extra delivery this year. On Christmas night, operating on written instructions from our two boys, the bearded one will swoop down to deliver a flock of chickens to an unsuspecting villager in the developing world. It's hard to know who will be more weirded-out: the hard-working farmer, looking up to see an overdressed symbol of northern Christian hegemony bearing down upon her with his deeply sinister laugh; or the reindeer, prey animals who will be jittery and nervous as they scent the local fauna; or the chickens themselves, jet-lagged and mad yet no doubt elated to have escaped the northern hemisphere at this dangerous time for fowl. The camera pulls out to reveal the sleigh looking incongruous amid mud huts, while white chicken feathers float like snowflakes through the tropical night. The soundtrack is We Wish You a Merry Christmas played on a thumb piano. That's basically the title sequence of this year's Down with the Kids Christmas special, which is called, A Poultry Donation.

The shot cuts to suburbia with the caption, "three weeks earlier". My family disembarks from our dented Renault Scenic, symbolising our status as westerners. There's a Christmas tree on the roof rack: we take it inside, and stick it in a bucket, and my wife and I exchange smug glances as our boys decorate only the low branches of it and smash only half the baubles. The Christmas presents are all bought, an optimal whisky-to-Nurofen ratio has been established, and our baby girl gurgles happily while Sinatra croons We Wish You A Merry Christmas on the stereo. But wait. There's something missing. Ah yes, that's it: the true meaning of Christmas. We gather the boys and ask whether there's anyone less fortunate than ourselves who we should be thinking of, this Christmas time. "Yes!" shouts our three-year-old. "Lucy!" Lucy is his grandparents' terrier. "Apart from Lucy," we say. Our six-year-old sticks up his hand. "Oooh!" he says, "I know! The poor children!" It seems they've covered this in school, along with spelling and five-a-day vegetables. There follows a genuinely touching scene where the boys race upstairs, empty their piggy banks, and rush back down with a football sock full of pennies. After counting, it turns out the boys have £8.54 to make the world a fairer place. We agree to supply top-up funds in case it isn't enough.

Christmas is a chance to teach kids two things that will serve them in life: compassion, and comparison shopping. We work out how to get the most goodwill for our loot. Live animal donations to overseas farming families quickly emerge as the kids' favourite, and chickens are their preferred option.

It turns out that Save the Children will do 40 chickens to a poor family for £29, or one piglet for the same price. Cafod will do an unspecified number of chickens for £20 but, winningly, they will do two piglets for £25. This is where our Christmas movie borrows a scene from Russel Crowe in A Beautiful Mind. We show our working on the windows with wax pencils. Assuming that the value differential for their chickens is equal to that of their pigs, then Cafod should be providing 64 chickens for £20. The maths behind this is so complex that I go mad while doing it and it falls to my wife to key in the order.

As the end credits roll, Sinatra and the thumb piano merge in unsettling discord. The movie goes to split-screen. In one frame, our three kids are tucked up asleep in their beds on Christmas Eve, while in the other frame, three little kids in Africa are kept awake by chickens.